1. Field of the Invention
Embodiments of the invention generally relate to the field of electronic manufacturing processes and devices, more particular, to methods of etching and depositing silicon-containing materials while forming electronic devices.
2. Description of the Related Art
Electronic devices such as semiconductor devices are fabricated by an assortment of steps including the deposition and removal of silicon-containing materials. The deposition and removal steps as well as other process steps may cause the substrate surface containing a silicon-containing material to become rough and/or bare contaminants. Also, particulates and other contaminants accumulate on the interior surfaces within a process chamber during the deposition and removal steps. The particulates may eventually further contaminate the substrate surface. Rough or contaminated substrate surfaces generally lead to poor quality interfaces which provide poor device performance and reliability.
Etching processes have been developed to combat contaminants and roughness on substrate surfaces. However, the traditional etching processes have some draw backs. Usually, etchants, such as hydrogen chloride (HCl), require a high activation temperature in order to remove silicon-containing materials. Therefore, etching processes are often conducted at temperatures of 1,000° C. or higher. Such high temperatures are not desirable during a fabrication process due to thermal budget considerations, possible uncontrolled nitridation reactions or over-etching to the substrate surface and loss of economically efficiencies. Etching processes with such extreme conditions may damage interior surfaces within the chamber, such as thermal quartz liners. Chlorine (Cl2) has been used to remove silicon-containing materials during etch processes at lower temperatures than processes that utilize hydrogen chloride etchants. However, chlorine reacts very quickly with silicon-containing materials and thus the etch rate is not easily controllable. Therefore, silicon-containing materials are usually over etched by processes using chlorine gas.
Also, traditional etching processes generally are conducted in an etching chamber or a thermal processing chamber. Once the etching of the silicon-containing material is complete, the substrate is transferred into a secondary chamber for a subsequent deposition process. Often, the substrate is exposed to the ambient environment between the etching process and the deposition process. The ambient environment may introduce water and/or oxygen to the substrate surface forming an oxide layer.
Prior to the etching process or the deposition process, a substrate is usually exposed to a pre-treatment process including a wet clean process (e.g., a HF-last process), a plasma clean or an acid wash process. After a pre-treatment process and prior to starting an etching process, the substrate may have to reside outside the process chamber or controlled environment for a period of time called the queue time (Q-time). During the Q-time, the substrate is exposed to ambient environmental conditions that include oxygen and water at atmospheric pressure and room temperature. The ambient exposure forms an oxide layer on the substrate surface, such as silicon oxide. Generally, longer Q-times form thicker oxide layers and therefore more extreme etching processes must be conducted at higher temperatures and pressures to maintain throughput.
Therefore, there is a need to have an etching process for treating a silicon-containing material on a substrate surface to remove any surface contaminants contained thereon and/or to smooth the substrate surface. There is also a need to be able to treat the substrate surface within a process chamber which could subsequently be used during the next process step, such as to deposit an epitaxy layer. Furthermore, there is a need to maintain the process temperature at a low temperature, such as below 1,000° C., and preferably below 800° C., even for substrates that have endured long Q-times (e.g., about 10 hours). Also, there is a need to reduce particulate accumulation on the interior surfaces of a process chamber, while not damaging these interior surfaces.